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Coypu and Nutria
Myocastor coypus is native to South America. Its distribution
ranges from middle Bolivia and southern Brazil to Tierra del Fuego.
As a result of escapes and liberations from fur farms, feral
populations now occur in Europe, Asia, and North America.
Nutrias inhabit marshes, lake edges, and sluggish streams,
especially in areas with emergent or succulent vegetation along the
banks. They are chiefly lowland animals, but may range up to 1,190
meters in the Andes. Although they generally prefer fresh water, the
population of the Chonos Archipelago in Chile occurs in brackish and
salt water.
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Coypu and Nutria
Myocastor coypus looks like a large, robust rat. Its body is highly
arched, and the head is large and almost triangular. The ears and
eyes are small and are located in the upper part of the head. The
incisors are broad, with orange-pigmented anterior surfaces. The
legs are short. The hind feet are much longer than the forefeet, and
contain five digits; the first four are connected by webbing, and
the fifth is free. The forefeet have four long, flexible, unwebbed
digits and a vestigial thumb. The tail is long and rounded. Females
have four pairs of thoracic mammae that are situated well up on the
sides of the body. The pelage consists of two kinds of hair, soft
dense underfur, and long coarse guard hairs that vary from yellowish
brown to reddish brown. The underfur is dark gray, and it is denser
on the abdomen. The chin is covered by white hairs, and the tail is
scantily haired.
Reproduction
Myocastor coypus is polyestrus. The length of the estrus cycle is
variable; intervals between cycles may range from 5 to 60 days.
Nutrias are nonseasonal breeders. The gestation period is long,
varying from 127 to 139 days. There is a post-partum estrus within 2
days of parturition. Mean litter size in general varies from three
to six, although it may range from 1 to 13. Factors affecting
reproductive potential of nutria are food type and availability,
weather conditions, predators and disease.
Sexual maturity is attained when young are only 6 months old.
Females care exclusively for the young. Newborns are fully furred,
and have their eyes open. They weigh approximately 225 grams each,
and rapidly gain weight during the first 5 months. The lactation
period extends for about 8 weeks.
The potential longevity of Myocastor coypus is 6 years.
Behavior
Myocastor coypus is semiaquatic. Individuals can remain submerged
for more than 10 minutes. They are most active at night. Most of the
active period is spent feeding, grooming, and swimming. They
commonly make platforms of vegetation, where they feed and groom
themselves. For shelter nutria construct burrows, which may be a
simple tunnel or a complex system containing passages that extend 15
meters or more and chambers that hold crude nests of vegetation.
Nutria also make runways through the grass and wander within a
radius of about 180 meters of their dens. Myocastor coypus is highly
gregarious. Groups usually consists of 2 - 13 animals and are
composed of related adult females, their offspring, and a large
male. Young adult males are occasionally solitary. Generally,
nutrias remain in one area throughout their lives.
Home range is fairly constant in spite of population density. The
average home range for female nutria is 2.47 ha, while for males it
is 5.68 ha.
Nutria probably communicate through tactile, chemical, and auditory
channels. Their eyesight is limited.
Food Habits
Nutria are herbivorous. The diet consists largely of aquatic
vegetation: stems, leaves, roots, and even bark. They may use logs
or other floating objects as feeding platforms.
In captivity they should be offered a complete diet of rodent lab blocks, and rat or mouse
mix, with bits of fruit or veggies regularly. Cheerios or wheat
bread are great treats, in small quantities. Do NOT feed chocolate,
fried foods, salted foods, candy or junk food! They may enjoy
crickets and mealworms if they are captive bred, never feed wild
insects as they may carry parasites. Vitamins, like Nutri-Cal are a good addition to their diet, and added calcium
during nursing and growth due to demands on their systems at those
times, but take care not to overdo it. Water bottles should be used
to proved constant, clean water. Ceramic or stoneware food dishes
work well for keeping seeds or fresh foods off the floor, and a wire
mesh hopper that allows them to eat the lab blocks through without
extra waste.
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